CLINICAL REPORT
An approximately 8-month-old female kitten was admitted to the hospital with an apparent traumatic hernia of the left abdominal wall. She was also pregnant. Two students found her in the parking lot of their apartment complex. They reported that she had been seen in the area for a few weeks and appeared normal the day before. That same afternoon, she was taken to surgery. At laparotomy, an OVH was performed on a large gravid uterus. A 2 cm tear in the dorsolateral abdominal wall was found with duodenum and greater omentum in the SQ space. A 1 cm tear in the duodenum was apparent. Ingesta contaminated the SQ space and the abdomen. After repair and closure of the abdomen, the SQ site was lavaged with the Betadine and a penrose drain placed. The kitten was unexpectedly painful the first two days post-operatively, but improved on SQ fluids and Cefazolin. By day 3, she was eating and grooming. Six days post-op a necrotic area became apparent near the site of the hernia. A 20cm by 10cm area of se-vere skin, fat and muscle necrosis was extensively debrided, flushed and bandaged. Closure was impossible because of the size of the defect and the degree of infection. For pain associated with the wounds and bandage changes, a 25ug Fentanyl patch was employed. Enrofloxacin and Cefazolin were given every 12 hours. Bandage changes occurred daily. The wound was lavaged with Betadine or Chlorhexiderm at each bandage change. A topical cephalosporin was applied during bandage changes. A second debridement was performed 3 days later. At that time, the margins of the wound extended from the scapula distally to the inguinal region and from the dorsum ventrally beyond the midline to the other side of the abdomen, approx. 23 by 20 cm. (Figure 1) This extent of this wound was about 40% of the trunk or axial area. She was not expected to survive. On the tenth day of hospitalization, hyperbaric therapy began." All other treatments were continued as described. She was placed in a small plexi-glass induction chamber commonly used in veterinary medicine with inflow and outflow connections. (Figure 2) Each session, called a "dive", lasted over one hour and took place at 2.36 atmospheres within the diving chamber. 100% oxygen was delivered into the chamber and expired air passively evacuated from the chamber. After 2 dives, a granulation bed began to form. Evidence of purulence dramatically diminished. Emphysema appeared in both back legs due to air leakage from the caudal ingui-nal margin of the defect. Both back legs were wrapped in a cruciate pattern integrated with the abdominal wrap. All other therapy contin-ued. The emphysema in her legs resolved as wound contracture proceeded and adhesion of the skin and SQ to the body wall began. . Healing continued rapidly. After eight days, the wound bed appeared increasingly vascular and became more painful as nerve endings surfaced. The ventral margins of the wound began to bleed during bandage placement. After 2 weeks, the wound bed had contracted to 9 by 10 cm, approx. 1/5 the original size. After four weeks of hyperbaric sessions, the dorsal margins of the wound were apposed. Ventrally the wound measured 8 by 2 cm. (Figure 3) Bandaging was discontinued after one month. In all, she dove in 32 separate ses-sions for a total of 2430 minutes. A scar appeared at the most central aspect of the wound where the two wound margins apposed. It is a thin line that travels from the dorsal lumbar area beyond the mid-line. It is approx. 5 mm wide at its widest point and is the only part of her body where far re-growth has not occurred.

Discussion

It is highly characteristic of necrotizing fasci-it is that the spread of the fascial necrosis is more extensive than the visible changes of the skin. The apparently normal skin and subcuta-neous tissue are loosened from the underlying necrotic fascia over a great distance from the original wound. Skin necrosis is secondary to thrombosis of subcutaneous blood vessels. In this case, the subcutaneous layer was thin and the skin became involved within 5 days. The kitten was extremely painful, became less so and then very painful during the first weeks of hyperbaric therapy. Hyperbaric oxygen therapy can be ad-ministered in an individual pressurized deliv-ery chamber or in a multi-position chamber. In this case, a chamber large enough to accomo-date at least six humans was used. Treatment regimens vary according to the disorder. De-livery of 100% oxygen at 2.0 to 2.4 ATA is standard for adult human patients. 2 Oxygen was delivered at 2.36 ATA, usually for 50 minutes with 15 minute com-pression (before) and decompression (after) phases. Breathing oxygen at this pressure in-creases oxygen tension in the capillaries that surround ischemic tissue and promotes oxy-gen diffusion from the capillaries to the tissue. Hyperbaric oxygen provides a signifi-cant increase in tissue oxygenation in the hy-poperfused, infected wound. This elevation in oxygen tension induces powerful positive changes in the wound repair process. HBO directly enhances fibroblastic replication, col-lagen synthesis and the process of neovascu-larization in ischemic tissue. By providing mo-lecular oxygen at the cellular level it also in-creases leukocyte bactericidal activity. The hyperoxic conditions increase the production of intracellular and extracellular oxygen-derived free radicals in leukocytes and phagocytes, enhancing the bacteriocidal ef-fects on strict anaerobic organisms and some microaerobic organisms. This can be roughly summarized as stimula-tion of the host defense and repair mecha-nisms. Hyperbaric oxygen therapy is a useful technique in the management of problem wounds in which hypoxia and/or infection are the underlying etiologic factors.

References:

Bakker, Jan Dirk, SelectedAerobic and Anaerobic Soft Tissue Infections, Diagnosis and the Use of Hy-perbaric Oxygen as an Adjunct, in Hyperbaric Medi-cine Practice, p. 396-417.

Hosgood, Elkins and Hill, "Hyperbaric Oxygen Ther-apy: Mechanism and Potential Applications", The Compendium of Continuing Education, Vol. 12 No. 11, 1990, p. 1589-1593

Inquiries about therapy may be made to the author or:
Western Hyperbaric, L.L.C.
Mr. Mitch Hoggard, President
3880 Morrow Ln., Suite 4
Chico Ca. (530) 894-3288

Matos and Nunez, Enhancement of Healing in Se-lected Problem Wounds, in Hyperbaric Medicine Practice, p. 590-611.

ABOUT THE AUTHOR:

Elizabeth Colleran is a 1990 graduate of Tufts University School of Veterinary Medicine. She completed a one year in-ternship at Southshore Veterinary Asso-ciates before moving to California. In 1996, she was awarded a Master of Sci-ence degree in Animals and Public Policy from Tufts University School of Veteri-nary Medicine. She owns Chico Hospital for Cats, an AAHA hospital in Chico.